1. Field of the Invention
The invention relates to compositions of proteins effective as vaccines to induce immunity and protect animals against infection by Mycobacterium avium subspecies paratuberculosis. 
2. Background of the Invention
Paratuberculosis vaccine studies have demonstrated the induction of both cellular and humoral immune responses, however, it is widely accepted that vaccination will not prevent infection. Some benefits of vaccination include reduced fecal shedding of Mycobacterium avium subspecies paratuberculosis (MAP) and reduced clinical signs in infected animals, with evidence suggesting a reduction in the incidence of disease within herds or severity of disease for individual animals (Kalis et al. Use of long-term vaccination with a killed vaccine to prevent fecal shedding of Mycobacterium avium subsp. paratuberculosis in dairy herds. Am. J. Vet. Res. 2001. 62:270-4; Begg et al. Vaccination of sheep against M. paratuberculosis: immune parameters and protective efficacy. Vaccine. 2005. 23:4999-5008; and Juste et al. Significant reduction in bacterial shedding and improvement in milk production in dairy farms after the use of a new inactivated paratuberculosis vaccine in a field trial. BMC Res Notes. 2009. 2:233-9). The heat-killed whole cell vaccine that is approved for use in the US (Mycopar, Fort Dodge Animal Health) is not ideal because of potential adverse reactions, including severe inflammation and granuloma formation at the injection site. In addition, vaccination with whole cell vaccines has been shown to interfere with bovine tuberculosis skin testing and serologic detection of MAP infected animals (Köhler et al. Immune reactions in cattle after immunization with a Mycobacterium paratuberculosis vaccine and implications for the diagnosis of M. paratuberculosis and M. bovis infections. J Vet Med B. 2001. 48:185-95; Muskens et al. Evaluation of the long-term immune response in cattle after vaccination against paratuberculosis in two Dutch dairy herds. Vet. Microbiol. 2002. 86:269-78; and Nedrow et al. Antibody and skin-test responses of sheep vaccinated against Johne's disease. Vet Immunol Immunopathol. 116:109-12). Developing subunit or DNA vaccines would significantly reduce or eliminate some of the troubling aspects of the whole cell vaccine without sacrificing beneficial properties.
Several MAP proteins or protein complexes have demonstrated success for use as subunit vaccines, including a 70 kDa heat shock protein, a 74F polyprotein, and a mixture of Ag85/SOD proteins. Immunization with these protein or protein complexes has provided protection against MAP challenge in mice, cattle and goat models, resulting in reduced colonization of tissues and decreased shedding in the feces (Koets et al. Mycobacterial 70 kD heat-shock protein is an effective subunit vaccine against bovine paratuberculosis. Vaccine. 2006. 24:2550-9; Chen et al. Immune responses in mice to Mycobacterium avium subsp. paratuberculosis following vaccination with a novel 74F recombinant polyprotein. Vaccine. 2008. 26:1253-62; and Kathaperumal et al. Vaccination with recombinant Mycobacterium avium subsp. paratuberculosis proteins induces differential immune responses and protects calves against infection by oral challenge. Vaccine. 2008. 26:1652-63). Each of these subunit vaccines has demonstrated that they are able to induce both cell-mediated and humoral immune responses in the respective hosts, suggesting strong protective measures. Further, it was recently demonstrated that the Hsp70 subunit vaccine does not cross-react with the comparative cervical skin test, a diagnostic tool commonly used for bovine tuberculosis in the field (Santema et al. Heat shock protein 70 subunit vaccination against bovine paratuberculosis does not interfere with current immunodiagnostic assays for bovine tuberculosis. Vaccine. 2009. 27:2312-19). Positive responses to AvPPD were noted in all vaccinated animals, however, responses to BoPPD were demonstrated only for cattle vaccinated with whole cell vaccine (Gudair) and not for those vaccinated with Hsp70 (Santema et al. ibid), demonstrating that a subunit vaccine can be more discriminative for identification of animals infected or vaccinated against MAP versus those animals infected with M. bovis. 
However, despite these advances, the need remains for improved vaccines for protecting animals against paratuberculosis. 